Reishi mushroom is a fungus that holds an important place in the traditional medical systems of China, Japan, Korea and other Asian countries for its health-promoting effects. It is used as an immunostimulant by patients with HIV and cancer. The active constituents include both beta-glucan polysaccharides and triterpenes.
Extracts of reishi were shown to have immunomodulatory (2) (3) (4) (5) (12), renoprotective (9), anti-inflammatory (36), and hepatoprotective (37) properties both in vitro and in vivo. Clinical studies indicate its benefits in improving lower urinary tract symptoms (LUTS) in men (10) (20), and in exerting mild antidiabetic effects and improving dyslipidemia (29). However, randomized controlled trials do not support the use of reishi to address cardiovascular risk factors associated with type 2 diabetes (38).
Reishi has also been studied for its anticancer potential. In vitro and animal studies indicate that it has antiproliferative(39) and chemopreventive effects (21), alleviates chemotherapy-induced nausea (13), enhances the efficacy of radiotherapy (22), and increases the sensitivity of ovarian cancer cells to cisplatin (27). It may also help prevent cisplatin-induced nephrotoxicity (28).
In small clinical studies, reishi increased plasma antioxidant capacity (6) (7), and enhanced immune responses in cancer patients (8) (40). In another study, a water-soluble reishi extract appeared to suppress development of colorectal adenomas (41). Remission of hepatocellular carcinoma (HCC) was reported in a few cases in a single study (23). Another case study series suggests benefits for gastrointestinal cancer patients (42). However, further research is needed to establish use of reishi as an anticancer agent (30).
An in vitro study reported that reishi mushroom extract has toxic effects in leukocytes (14). Therefore, more research is needed to determine its safety and effectiveness as an adjunctive cancer treatment.